Usp14 deficiency removes α-synuclein by regulating S100A8/A9 in Parkinson’s disease

Ubiquitin-proteasome system dysfunction triggers α-synuclein aggregation, a hallmark of neurodegenerative diseases, such as Parkinson’s disease (PD). However, the crosstalk between deubiquitinating enzyme (DUBs) and α-synuclein pathology remains unclear. In this study, we observed a decrease in the level of ubiquitin-specific protease 14 (USP14), a DUB, in the cerebrospinal fluid (CSF) of PD patients, particularly females. Moreover, CSF USP14 exhibited a dual correlation with α-synuclein in male and female PD patients. To investigate the impact of USP14 deficiency, we crossed USP14 heterozygous mouse (USP14+/−) with transgenic A53T PD mouse (A53T-Tg) or injected adeno-associated virus (AAV) carrying human α-synuclein (AAV-hα-Syn) in USP14+/− mice. We found that Usp14 deficiency improved the behavioral abnormities and pathological α-synuclein deposition in female A53T-Tg or AAV-hα-Syn mice. Additionally, Usp14 inactivation attenuates the pro-inflammatory response in female AAV-hα-Syn mice, whereas Usp14 inactivation demonstrated opposite effects in male AAV-hα-Syn mice. Mechanistically, the heterodimeric protein S100A8/A9 may be the downstream target of Usp14 deficiency in female mouse models of α-synucleinopathies. Furthermore, upregulated S100A8/A9 was responsible for α-synuclein degradation by autophagy and the suppression of the pro-inflammatory response in microglia after Usp14 knockdown. Consequently, our study suggests that USP14 could serve as a novel therapeutic target in PD. Supplementary Information The online version contains supplementary material available at 10.1007/s00018-024-05246-8.


Introduction
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by impaired movements, including tremor and bradykinesia [1].Pathologically, PD is marked by the loss of dopaminergic neurons and the presence of Lewy body inclusions composed of aggregated α-synuclein in the nigrostriatal pathway [2,3].Additionally, SNCA (encoding α-synuclein) mutations are critical genetic risk factors for PD [4][5][6], emphasizing the significance of α-synuclein pathology in PD pathogenesis.The ubiquitin proteasome system degrades misfolded proteins, and its malfunction contributes to the formation of α-synuclein aggregates in PD [7].In the classical ubiquitin proteasome system pathway, ubiquitin-activating enzyme (E1) is recruited to activate ubiquitin, which is then transferred to the ubiquitin-conjugating enzyme (E2) and subsequently conjugated to lysine residues within the substrate by ubiquitin ligase (E3).Several lysine residues, such as K12, K21, K23, and K34, have been identified in α-synuclein [8,9].Deubiquitinating enzymes (DUBs) can cleave ubiquitin from proteins, stabilizing the substrate.A deubiquitination protein, ubiquitin C-terminal hydrolase L1 (UCHL1), is considered a risk gene for PD [10,11].It loss stabilizes pyruvate kinase and induces energy-dependent mitophagy, improving PD-related phenotypes [12].Furthermore, S-nitrosylation of UCHL1 promotes α-synuclein aggregation [13], suggesting its close relationship with PD pathology.However, it is unclear how other DUBs contribute to the pathogenesis of PD.

USP14 is correlated with α-synuclein level in PD patients
Since USP14 inhibition promotes PINK1/Parkin-mediated mitophagy [26], and USP14 modulates the degradation of tyrosine hydroxylase [27], the rate-limiting enzyme in dopamine biosynthesis, we hypothesize that USP14 may be related to PD.First, we detected the CSF levels of α-synuclein and USP14 in controls and PD patients.Consistent with a previous study [28], CSF α-synuclein level was significantly decreased in both male and female PD patients (Fig. 1a and b).In the present study, the CSF USP14 level was lower in PD patients, particularly females (Fig. 1c and  d).Pearson correlation analysis demonstrated no correlation between USP14 and α-synuclein levels in the control group (Fig. 1e-g).However, CSF USP14 level was positively related to the α-synuclein level in male PD patients and negatively related in female PD patients (Fig. 1h-j).These data suggest that the relationship between USP14 level and α-synuclein pathology differs between genders.
We assessed α-synuclein deposition under Usp14 deficiency.Exogenous human α-synuclein and endogenous phosphorylated α-synuclein at Ser129, a key hallmark of Lewy bodies, were significantly increased in the SN and striatum of male and female A53T-Tg mice (Fig. 3a-f).USP14 +/− ; A53T-Tg mice showed reduced expression of phosphorylated α-synuclein compared to male and female A53T-Tg mice, whereas female mice had reduced human α-synuclein expression in the SN (Fig. 3a-d).Moreover, compared to A53T-Tg mice, the expressions of human α-synuclein and phosphorylated α-synuclein were inhibited in the striatum of female USP14 +/− ; A53T-Tg mice (Fig. 3e  and f).These results suggest that Usp14 deficiency reversed α-synuclein deposition in female A53T-Tg mice.

Usp14 inactivation increased S100A8/A9 expression in female A53T-Tg mice
We used RNA-sequencing (RNA-seq) to explore the mechanisms underlying the aforementioned changes.We explored the differentially expressed genes (DEGs) in the SN between male and female A53T-Tg and USP14 +/− ; A53T-Tg mice (Fig. 4a and b; Supplementary Fig. 1a and b).In total, 49 DEGs were shared by male and female mice (Fig. 4c).In male mice, gene ontology pathways enriched by the upregulated DEGs were related to mitochondrial function, such as the mitochondrial respiratory chain and ATP metabolism (Fig. 4d), whereas in female mice, the pathways were related to synaptic function, such as neurotransmitter transport, axon development, and dopamine transport (Fig. 4e).
We investigated the DEGs enriched in locomotor behavior and dopamine transport, which were closely related to PD (Fig. 4f).Notably, the expression of most DEGs enriched in these pathways was increased in female mice and decreased in male mice (Fig. 4f).Furthermore, the expression patterns of S100A8 and S100A9 demonstrated a similar pattern (Fig. 4f), with the S100A8/A9 expression being increased in the SN pars compacta (SNpc) of USP14 +/− ; A53T-Tg mice compared to A53T-Tg mice (Fig. 4g and h).(e-j) Correlation between USP14 and α-synuclein in control and PD groups was assessed by Pearson's correlation analysis.Results are expressed as mean ± SEM. ** p < 0.01, * p < 0.05 vs. controls.Statistical significance was determined using Student's t-test in the center zone in OFT (Fig. 5b-e).Furthermore, male USP14 +/− + AAV-hα-Syn mice exhibited a longer climbing time compared to AAV-hα-Syn mice (Fig. 5f).These results suggest Usp14 inactivation damaged the motor function following AAV-hα-Syn administration.Female USP14 +/− + AAV-hα-Syn mice demonstrated improved motor coordination compared to AAV-hα-Syn mice (Fig. 5g), indicating Usp14 inactivation may be beneficial for AAV-hα-Syn administration.The grip strength was not significantly

Differential effects of Usp14 inactivation on male and female AAV-hα-Syn mice were mediated by S100A8/A9
Considering that the S100A8/A9 expression was increased in the SN of female USP14 +/− ; A53T-Tg mice, we further explored this finding in AAV-hα-Syn mice.The DEGs between male and female AAV-hα-Syn and USP14 +/− + AAV-hα-Syn mice are presented in Fig. 8a and b and Supplementary Fig. 2a and b.There were 16 DEGs shared by male and female mice (Fig. 8c).Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that the pathways enriched by upregulated DEGs in male mice were mainly focused on synaptic function (such as glutamatergic synapse) and inflammatory response, whereas in female mice, of human α-synuclein and phosphorylated α-synuclein in response to paquinimod in male USP14 +/− + AAV-hα-Syn mice (Fig. 9c).However, paquinimod reversed the decreased phosphorylated α-synuclein expression in female USP14 +/− + AAV-hα-Syn mice, whereas there were no significant We evaluated the S100A8/A9 expression in response to the S100A8/A9 antagonist (Paquinimod).Paquinimod substantially reduced the S100A9 expression in the SNpc of male and female USP14 +/− + AAV-hα-Syn mice (Fig. 9a and  b).There were no significant alterations in the expressions ** p < 0.01 vs. AAV-GFP; ## p < 0.01, # p < 0.05 vs. AAV-hα-Syn.Statistical significance was determined using one-way ANOVA and Tukey's test for post hoc comparisons phosphorylated α-synuclein, but not human α-synuclein, expression in hα-Syn fibril-treated BV2 cells (Fig. 10a), which was consistent with our in vivo findings.Furthermore, Usp14 knockdown increased the S100A8/A9 expressions at the protein and mRNA levels (Fig. 10b and c).Usp14 knockdown increased the LC3 II/I ratio and Beclin 1 expression (Fig. 10d), suggesting that autophagy was increased.Usp14 knockdown also suppressed NF-κB and IκBα phosphorylation and reduced the mRNA expressions of pro-inflammatory cytokines (IL-6, TNF-α, and IFN-γ) (Fig. 10e and f).On the other hand, hα-Syn fibril increased the mRNA expressions of pro-inflammatory cytokines (TNF-α and IFN-γ) and microglial receptors (CX3CR1 and CSF1R) (Supplementary Fig. 5A-C).Furthermore, Usp14 knockdown decreased the mRNA expressions of TNF-α and IFN-γ (Fig. 10g).To explore whether the effects of Usp14 effects on human α-synuclein expression (Fig. 9d).We further confirmed these results by staining for phosphorylated α-synuclein in dopaminergic neurons in the SNpc (Fig. 9e  and f).These findings suggest that the effects of Usp14 deficiency on the α-synuclein pathology in AAV-hα-Syn mice may be mediated by S100A8/A9.
knockdown are mediated by S100A8/A9, we administered paquinimod in vitro (Supplementary Fig. 6).Paquinimod attenuated the effects of Usp14 knockdown on increasing the LC3II/I ratio and Beclin 1 expression, as well as inhibiting NF-κB activation (Fig. 10h and i).These findings suggest that the effects of Usp14 knockdown on autophagy and NF-κB in BV2 cells are mediated by S100A8/A9.There were no significant differences in CSF S100A8/A9 levels between controls and PD patients.Furthermore, we did not observe any correlation between CSF S100A8/A9 the effects of Usp14 deficiency on α-synuclein clearance.Our study reveals a novel relationship between S100A8/A9 and DUBs in neurodegenerative diseases.
Finally, we found that Usp14 inactivation reduced the proinflammatory response.Previously, USP14 was reported to mediate IκBα degradation and thus induce NF-κB activation [32].USP14 inhibition suppressed the inflammatory reaction [45,46].As a potential downstream target of USP14 inhibition, S100A8/A9 usually triggers inflammation [47,48] but also exerts anti-inflammatory effects by inducing IL-10 production, suppressing NF-κB activation, and reducing intracellular calcium signaling in immune cells [49][50][51].In the present study, we found that Usp14 knockdown suppressed NF-κB activation and reduced microglial activation and pro-inflammatory cytokine release in female A53T-Tg and AAV-hα-Syn mice.These neuroprotective effects were positively correlated with S100aA/A9 upregulation, whereas S100A8/A9 abolished the anti-inflammatory effects of Usp14 knockdown.Our findings suggest that Usp14 inactivation may promote microglial shift from the deleterious M1 phenotype to the neuroprotective M2 phenotype, leading to α-synuclein phagocytosis and an antiinflammatory response.Next, we investigated how Usp14 inactivation aggravates α-synuclein pathology and the proinflammatory response in male AAV-hα-Syn mice.Usp14 inactivation increases S100A8/A9 deposition in male AAVhα-Syn mice, although its level was much lower than that in female mice.We hypothesize that the higher S100A8/A9 expression can induce autophagy and exert anti-inflammatory effects.Furthermore, estrogen may play a role in determining the effects of Usp14 deficiency.
Our results demonstrated a dual relationship between CSF USP14 and α-synuclein levels in PD patients.Usp14 deficiency improved the behavioral abnormities and pathological α-synuclein deposition in female A53T-Tg and AAVhα-Syn mice.Furthermore, Usp14 inactivation attenuates the pro-inflammatory response in female AAV-hα-Syn mice.We also found that S100A8/A9 may be the downstream target of Usp14 deficiency.Based on our findings, USP14 may represent a promising therapeutic target for PD.

Patient characteristics
CSF samples were collected from 41 PD patients (mean age: 66.23 ± 7.42 years; 17 males and 24 females) and 41 healthy controls (mean age: 54.88 ± 13.69 years; 21 males and 20 females).The participants were recruited from the First Affiliated Hospital of Guangzhou Medical University.PD was diagnosed according to the UK Parkinson's Disease
First, CSF USP14 may be a promising indicator for PD.Recent accumulating evidence reveals that intact 20 S proteasomes in the circulatory system (c-proteasomes) and related plasma proteins represent pathophysiological conditions [36].USP14 is associated with 19 S and 26 S proteasomes [14,37], and it is conjugated with Ub, leading to 20 S proteasome gate opening [17], suggesting that USP14 may be involved in the production of c-proteasomes.In the present study, we detected decreased CSF USP14 expression in PD patients, particularly females.Furthermore, we found opposite relationships between CSF USP14 and α-synuclein expressions in male and female PD patients.Our results from USP14 +/− mice crossed with A53T-Tg or AAV-hα-Syn administration demonstrated that α-synuclein regulation by USP14 inactivation may be affected by gender, possibly due to the effects of hormones, such as estrogen.Conversely, we could not exclude the possibility of release of USP14 enzyme by damaged neural cells, such as neurons and microglia.Further studies are needed to examine the effects of circulating USP14.
Second, we evaluated the effects of Usp14 inactivation on α-synuclein pathology.Proteasome activation was associated with USP14 inhibition, which clears the tau oligomer [19].Furthermore, USP14 inactivation also induces autophagy by inhibiting K63 ubiquitination of Beclin 1, a key autophagy molecule [23,38,39].In line with a previous study, we also found that Usp14 knockdown increased Beclin 1 expression and autophagy, which may explain the observed clearance of α-synuclein deposition in female USP14 +/− ; A53T-Tg and USP14 +/− + AAV-hα-Syn mice.Mechanistically, we found that the effects of Usp14 inactivation are mediated by S100A8/A9.S100A8 and S100A9 exist as heterodimers and are expressed in neutrophils and monocytes.S100A8/A9 activation in the brain can induce microglial activation [30,40] and induce autophagy [41,42].Similar to our previous study and other studies, microglia can engulf the α-synuclein released by neurons by inducing microglial autophagy [43,44].We hypothesize that, under Usp14 deficiency, S100A8/A9 promotes microglial phagocytosis of α-synuclein, thereby improving the behavioral abnormalities in female A53T-Tg and AAV-hα-Syn mice.Pharmacological inhibition of S100A8/A9 diminishes BV2 cell culture and treatment BV2 cells were procured from the American Type Culture Collection (Manassas, VA, ATCC) and were cultivated in DMEM (Gibco, C11995500BT) medium supplemented with 10% fetal bovine serum (Invitrogen, Carlsbad, CA, USA) at 37 °C under 5% CO2 in an incubator.Small interfering RNA (siRNA) targeting the Usp14 sequence ) were custom-designed and synthesized by RioBio (Guangzhou, China).A negative-control siRNA was also provided by RioBio.The transfection procedure was similar to that described in our previous study [53].Briefly, the siRNA (100 nM) was diluted and incubated with ribo-FECT CP Reagent (RioBio) for 15 min at room temperature (RT).Subsequently, the mixture was added to the culture medium and incubated with BV2 cells.To detect the effects of Usp14 knockdown on α-synuclein pathology, BV2 cells were transfected with USP14 siRNA for 48-72 h, and 5 µg/ mL human α-synuclein preformed fibrils was added during the final 24 h, as stated previously [44].To examine the effects of S100A8/A9 inhibition after USP14 siRNA transfection, BV2 cells were treated with 50 µM paquinimod for the final 24 h.Then, the RNA and protein extracted from cellular samples were collected for RT-qPCR and Western blot analysis.

Animals
Heterozygous USP14 knockout (USP14 +/− ) mice with a C57BL/6J genetic background generously provided by professor Jinbao Liu from Guangzhou Medical University.USP14 +/− mice were crossed with wild-type (WT) C57BL/6J mice, and the genotypes of the offspring were identified using PCR (primers: F 5

'-T C C C A A A A T A A A T G T A A A G T C A A T and R 5'-A A G G T G G G T A G A G A A A A T A A A A G T)
. hSNCA*A53T-Tg mice (also known as A53T α-Syn mice) were obtained from the Shanghai Model Organisms Center, Inc. (Shanghai, China).Crossbreeding between USP14 +/− and A53T transgenic mice resulted in four genetic combinations: WT, A53T-Tg, USP14 +/− , and USP14 +/− ; A53T-Tg mice, which were further categorized in male and female subgroups.Adult (8-week-old) male and female C57BL/6J mice used for AAV-hα-Syn injection were procured from SPF Biotechnology Co., Ltd.(Beijing, China).The distribution of mice in each group was random and blinded, with age and sex being matched.Mice were housed in groups of 4-5 per cage under controlled conditions: a 12/12-h light/dark cycle, temperature of 22 ± 1 °C, and relative humidity of 60 ± 5%, with ad libitum access to food and water.The animal experiments were conducted in Society Brain Bank clinical criteria [52].The study protocol was approved by the Ethics Committee of the First Affiliated Hospital of Guangzhou Medical University.Written informed consent was obtained from all participants.Controls were matched with patients in terms of age and gender.

ELISA
The CSF levels of α-synuclein, USP14, and S100A8/A9 were examined using ELISA kits according to the manufacturer's protocols, as described previously [53].Optical density values were determined using a Multiscan Spectrum (PerkinElmer, MA, USA) at 450 nm, and the results are expressed as pg/mL or ng/mL.

Rotarod test
Rotarod test was performed similar to a previous study [44].Before the test, mice underwent a 3-day training on a Rotarod apparatus (Ugo Basile SRL, Gemonio, VA, Italy) at a constant speed of 10 rpm.On day 4, mice were placed on the Rotarod, and the speed was gradually increased from 4 rpm to 40 rpm within 5 min.The duration spent by each mouse on the rotating rod before falling was accurately recorded.Trials were terminated if a mouse fell off the rod or clung to the apparatus for two full rotations without walking or running.Each mouse was subjected to three trials, and the mean duration was recorded.

Western blot
Brain tissues and cultured cells were lysed using a RIPA buffer containing 1 mM PMSF (Beyotime, Shanghai, China).The lysates were homogenized using ultrasonication and then centrifuged to collect the supernatant.Protein concentrations in the supernatant were quantified using the BCA Protein Quantification Kit (Beyotime, Shanghai, China).The lysates were separated via SDS-PAGE and subsequently transferred onto PVDF membranes.The membranes were blocked at RT for 30 min, followed by incubation with primary antibodies overnight at 4 °C and HRP-conjugated secondary antibodies for 1 h at RT.Protein bands were visualized using an enhanced chemiluminescence system with a luminol reagent (Beyotime, Shanghai, China).The chemiluminescent signals were captured using the GeneGnome XRQ Chemiluminescence system (Gene Company, Hong Kong, China) and measured using ImageJ software.

Quantitative polymerase chain reaction (qPCR)
The qPCR was performed as described previously [54].Total RNA was extracted from cultured cells and SN tissues using TRIzol reagent (Invitrogen, San Diego, CA, USA).cDNA synthesis was performed using the cDNA Reverse Transcription Kit (Takara, Otsu, Japan).The qPCR was conducted using the Applied Biosystems 7500 Real-Time PCR System (Thermo Fisher Scientific, USA) with the following thermal cycling parameters: initial denaturation at 95 °C for 5 s, annealing at 55 °C for 30 s, and extension at 72 °C for 30 s.This cycle was repeated for 40 cycles to amplify the target sequences.TB Green Premix Ex Taq (Takara, Shiga, Japan) was used for the qPCR reactions, ensuring high sensitivity and specificity.Data were derived from three independent experiments, each with triplicate samples.The 2 −ΔΔCT method was used for data analysis, with Gapdh serving as the reference gene for normalization.Supplementary accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals (NIH Publications No. 8023, revised 1978) and were approved by the Institutional Animal Care and Use Committee of Guangzhou Medical University.

OFT
OFT was performed similar to our previous study [44].In brief, mice were placed within a 40 × 40 × 40-cm rectangular plastic enclosure, segmented into peripheral and central zones.Mice were allowed to explore freely for 15 min, and the movement speed, total distance traveled, and time spent in the central zone were recorded using a video tracking system (EthoVisione XT software, Beijing, China).

Grasping test
Grasping test was performed as described previously [44].A horizontal stainless-steel wire with a diameter of 1 mm was suspended 30 cm above the ground.Mice were carefully placed so that their forepaws gripped the wire, and their grasping ability was observed for 10 s.Scores were assigned depending on whether the mice successfully grasped with both hind legs (3 points) or one hind leg (2 points), failed to grasp with either hind leg (1 point), or fell (0 points).Mice underwent three trials, and the average score was recorded.

Pole climbing test
Pole climbing test was performed as described previously [44].Prior to the experimental procedure, mice were placed in a behavioral room for acclimatization for 30 min.The test involved a metal pole, with a diameter of 9 mm and length of 75 cm, wrapped in bandage gauze to enhance grip.Mice were gently positioned 7.5 cm away from the top of the pole.The time taken for each mouse to descend to the bottom was carefully recorded, with a maximum duration limit of 60 s for each trial.HTSeq v0.6.0, and the fragments per kilobase of transcriptper-million mapped reads for each gene were calculated, taking into account the gene length and read counts mapped to it.DEGs were identified using predefined thresholds of fold change > 1, false discovery rate < 0.1, and adjusted p < 0.05.The pathways of DEGs were analyzed using the R package (v 3.5.1).

Statistical analysis
Data are presented as mean ± standard error of the mean (SEM).Sample sizes were chosen based on the means and variation of preliminary data to achieve at least 80% power and allow for a 5% type I error.All calculations for sample sizes were done using an online sample size calculator (https://clincalc.com/stats/samplesize.aspx).Data were analyzed using Student's t-test, one-way analysis of variance followed by Tukey's post hoc test, as appropriate.Differences with a p-value < 0.05 were considered statistically significant.Statistical analyses were performed using GraphPad Prism 9.0 (GraphPad Software, La Jolla, CA, USA).P-values are represented as * p < 0.05 and ** p < 0.01.
Table 1 presents the detailed information regarding the primers use.

Immunohistochemistry and immunofluorescence assays
The mouse brain was fixed in 4% paraformaldehyde and dehydrated in 20-30% sucrose buffer for 3 days.The brains were embedded in OCT (Solarbio, Beijing, China) and then coronally sectioned at a thickness of 30 μm using a Leica cryostat.For immunohistochemical staining, Ultra-Sensitive™ SP (mouse/rabbit) IHC Kit (MXB KIT-9720, Fuzhou, China) was employed, involving DAB staining and subsequent dehydration and clearing.Imaging was conducted by scanning the slices using an optical microscope (CS2, Leica Microsystems, Germany).For immunofluorescence experiments, brain slices or fixed-cultured cells were blocked to prevent non-specific binding and then incubated overnight at 4 °C with primary antibodies, followed by incubation with fluorescently labeled secondary antibodies at RT for 1 h.The nuclei were counterstained with DAPI for visualization.The slides were imaged using a laser scanning confocal microscope (SP8, Leica Microsystems, Germany).The fluorescence intensity in these images was quantified using ImageJ software.

Transmission electron microscopy (TEM)
The ultrastructural morphology of synaptic vesicles in the SN tissue was analyzed using TEM, as stated previously [55].Following euthanasia of mice, the SN was promptly extracted and immersed in the TEM fixative at RT away from light for 2 h.Subsequently, the specimens were preserved at 4 °C.The samples were washed three times with 0.1 M phosphate buffer (pH 7.4), sequentially dehydrated in an ascending ethanol gradient, incubated in 100% acetone for penetration, and embedded in epoxy resin (812 embedding agent) for final embedding.Ultra-thin Sects.(60-80 nm) were obtained using a Leica ultramicrotome and stained with uranyl acetate and lead citrate.Finally, images of synaptic vesicles were captured and subjected to further analysis using a TEM (HT7700, Hitachi, Tokyo, Japan).

RNA-seq
RNA-seq was performed as described previously [54].In brief, RNA was extracted from SN using TRIzol (Invitrogen, Carlsbad, CA, USA).Subsequently, cDNA libraries were generated using the NEBNext® Ultra™ RNA Library Prep Kit for Illumina®, and these libraries were sequenced using a HiSeq 2500 instrument platform (San Diego, CA, USA).Novogene Inc. (Beijing, China) performed the sequencing process.Read counts were determined using

Fig. 1
Fig. 1 USP14 demonstrates dual correlation with α-synuclein in the CSF of PD patients.(a-d) The CSF levels of α-synuclein and USP14 in male and female controls (n = 41) and PD patients (n = 41) were assessed using ELISA.The control group included 21 males and 20 females, whereas the PD group included 17 males and 24 females.

Fig. 2
Fig. 2 Usp14 deficiency ameliorates the motor deficits in female A53T-Tg mice.(a) Crossing of USP14 +/− and A53T-Tg mice.(b-e) Representative traces, total travelled distance, movement speed, and time spent in the center zone in the open-field test.(f) Pole climbing test was used to examine bradykinesia in mice.(g) Rotarod test was used to examine motor coordination in mice.(h) Grasping test was used to examine the grip strength in mice.n = 12, 10, 7, and 10 for

Fig. 5 Fig. 6
Fig. 5 Usp14 deficiency improves the motor deficits in female AAV-h α-Syn-injected mice.(a) Experimental design for AAV-hα-Syn virus administration in male and female WT and USP14 +/− mice.(b-e) Representative traces, total travelled distance, movement speed, and time spent in the center zone in the open-field test.(f) Pole climbing test was used to examine bradykinesia in mice.(g) Rotarod test was used to examine the motor coordination in mice.(h) Grasping test was used to examine the grip strength in mice.n = 10, 10, 6, and 7 for male AAV-